Missing logs?

Just out of curiosity. I went and looked in my history

 

Firewall-Network and connections

 

and there was nothing noted in there. I know I had restarted my computer about 18 hours ago. Shouldn't that information be shown in the log? I know there were some items in there 18 hours ago. How long is that information retained there?

 

 

 

VistaHome Premium, 32 bit  Vista SP2

NIS 2010 17.8.0.5